1. Field of the Invention
The present invention relates to foamed cement slurries and additives as well as methods of cementing utilizing the foamed cement slurries and additives.
2. Description of the Prior Art
Foamed hydraulic cement slurries are commonly utilized in forming structures above and below ground. In forming the structures, the foamed hydraulic cement composition is pumped into a form or other location to be cemented and allowed to set therein. Heretofore, foamed cement slurries have included foaming and stabilizing additives which include components such as isopropyl alcohol that interfere with aquatic life. In addition, one or more of the components are often flammable and make the shipment of the foaming and stabilizing additives expensive. Thus, there is a need for foamed hydraulic cement slurries which include environmentally benign foaming and stabilizing additives that do not include flammable components.
In the construction and repair of wells such as oil and gas wells, foamed hydraulic cement slurries are often pumped into locations in the wells to be cemented and allowed to set therein. In primary well cementing, foamed cement slurries are extensively used to cement off-shore deep water wells wherein they encounter temperatures varying between 40° F.–50° F. The foamed cement slurries are pumped into the annular spaces between the walls of the well bores and the exterior surfaces of pipe strings disposed therein. The foamed cement slurries are compressible which prevents the inflow of undesirable fluids into the annular spaces and the foamed cement slurries set therein whereby annular sheaths of hardened cement are formed therein. The annular cement sheaths physically support and position the pipe strings in the well bores and bond the exterior surfaces of the pipe strings to the walls of the well bores whereby the undesirable migration of fluids between zones or formations penetrated by the well bores is prevented.